Wave movements in the sea and in large inland lakes constitute a potential source of energy that has scarcely been exploited so far. However various suggestions have been made to use the vertical movements of the sea for producing electrical power in a generator. Since a point on the sea surface makes a reciprocating vertical movement it is suitable to use a linear generator to produce the electric power.
WO 03/058055 discloses such a wave power unit where the moving part of the generator, i.e. the part that corresponds to the rotor in a rotating generator and in the present application called translator, reciprocates in relation to the stator of the generator. In that disclosure the stator is anchored in the sea bed. The translator is by flexible connection means, such as a wire, cable or a chain connected to a body floating on the sea. The present invention, however, is not limited to a wave power unit, in which the generator is a linear generator, but applies also to a conventional rotating generator. A wave power unit with a rotating generator is disclosed in WO/058054.
The floating body is by a wire connected to the moving part of the generator, i.e. the translator of a linear generator or the rotor of a rotating generator. When the floating body moves up and down, the wire does the same and transmits a force to the moving part of the generator such that it reciprocates or rotates. At such operation the wire will alternating be exposed to tensile forces and zero forces. The zero forces mainly occur at the ends of the reciprocating movements, but might also occur during the movement as such. When the wire is unloaded it might slack. When thereafter the force at either end of the wire begins to stretch the wire, initially a quick acceleration occurs until the wire is stretched and starts to take up the force. The result is that the wire at the end of this acceleration almost instantly alters from being unloaded to be exposed to a very high load, amplified by the dynamic effect at the sudden retardation. This is harmful to the wire and entails the risk of breakage of it.
A similar problem may be present in wires connecting the floating body to a stationary part of the submerged station as will be explained later.